It is sometimes required that a trigger-operated electrical device, such as a power tool, be continuously operated for an extended period of time at a desired speed setting. To alleviate fatigue in the user's finger operating the trigger, a locking mechanism may be provided to allow locking of the power tool at the desired speed of operation. Certain conventional trigger mechanisms may include a latch member disposed on the side of the trigger mechanism housing which must be manually moved with some degree of force into a locking position by one of the user's hands to effect locking of the trigger mechanism in to the desired speed setting. This is not only slow and tedious to lock the trigger mechanism into the desired speed setting, but is also slow and tedious to thereafter dislodge the latch member from its locked position. Furthermore such conventional locking systems may also compromise user safety as the user is required to use both hands to effect locking of the power tool. That is, one hand (usually the hand that is used to firmly grip/support the body of the power tool) is required to manually move the latch member disposed on the trigger housing with some force into its locked position whilst the other hand is required to squeeze the trigger at the desired speed setting. Other conventional locking systems may require the latch member to be moved in multiple orientations, for instance, by manually moving the latch member inwardly and then upwardly of the trigger housing. Again, these conventional locking mechanisms require two hands to be operated and risk of injury to the user is further exacerbated due to the awkward and unnatural movements required by one of the user's hand in manually moving the latch member in to the locked position.